RCD tripping

[markadams]

Hi,

Got called to a jobs due to the RCD tripping on the downstairs ring, as soon as the MCB for the ring is turned on the RCD trips.

I didn't have long but I did some quick tests, R1+R2 was fine on all sockets so I split the ring about half way and did an IR test on each side of the ring and got 0.01 ohm on both sides.

I had to go to another job but I am back tomorrow.

Any suggestions for what may cause this? or testing

 

[Octopus]

Murdoch,

I agree that it sounds very odd which is why I wanted to get some views on here, I have done a fair bit of fault finding but never had this scenario.

When you had split the ring, with both halves disconnected at the cu, did you check for continuity between them as it sounds like there is an interconnection

 

[markadams]

Everything is unplugged.

Assegayer, that was my next thought also, I just cant understand how it has a fault on both sides

 

[markadams]

Not yet Murdoch, will try tomorrow.

 

[Octopus]

Not yet Murdoch, will try tomorrow.

has to be your next test, but after rechecking the IR between the 3 cores

 

[happysteve]

Either two faults, or, there is another interconnection in the ring (ie wired up like an "8", not a "0").

Edit: oops, too slow!

 

[markadams]

A lot of work is being done in the house, a new boiler a month ago and new kitchen recently, they say nothing was being done when it tripped off.

 

[markadams]

It is generally vey poorly wired, none of the cpc's behind the sockets I looked at had any sleeving.

 

[assegayer]

yep as murdoch said, then just take it nice and easily, me personally I like to just do old fashion and bell things out and then label so i know which things are where and then you can track the fault relitavely quickly and i just use the rcd as the main tester lol keep splitting and checking if its okay best way IMO

 

[markadams]

Well I had another look and I have seen nothing like it. I disconnected one of the sockets about mid way and checked the resistance of r1 on both sides of the ring, and both sides gave approx 0.51 ohm, I then disconnected other sockets and on a 13 socket circuit only three made a difference to the reading, a couple gave open circuit on both sides. Customer has decided that they want it all redone correctly as a ring as every job in the house has been done wrong and installed by the DIY previous owner who had no clue.

 

[Midwest]

Jobs a good'un', if they want it rewired. By the sounds of it probably cheaper in the long run!

 

[markadams]

Jobs a good'un', if they want it rewired. By the sounds of it probably cheaper in the long run!

That's what I thought but I would love to know what they have done, the readings make no sense at all.

 

[Midwest]

You'll probably come across whilst rewiring